Method of manufacture of snap hooks



3am. 118 1949. A. L. MCKHNNON METHOD OF MANUFACTURE OF SNAP HOOKS Filed Feb 5, 1.945 5 Sheets-Sheet 9 QQ ,AATTORNEYS Jan. 18, 1949. A. L. MCKINNQN 2,459,735

l QBTHOD OF MANUFACTURE OF SNAP HOOKS INVENTOR ARCHlBALD L. McKmNoN Quw, WMQMJMATTORNEY5 Patented Jan. 18, 1949 UNITED STATES PATENT o F ce OFMANUFACTURE OF- SNAP HOOKS Archibald llfiMcKirinon, St. Cathafinea'Ontario, Canada, assignor to Columbus McKinnon Chain Corporation, Tonawanda, N; Y. Application February 5, 1945,, Serial No. 576,293

Claims.

This invention relates to improvements in snap hook devices, and toimproved methods for manufacturing like articles.

One of the objects of the invention is to provide' an improved snap hook of the type formed of'bent rod or wire stock, and having advantages ofllnc'reased ruggedness and stability against load failures comparedto'prior snap hooks of generally similar type. Another object of the invention is to provide an improved snap hook design which is. adapted to be fabricated in improved manner byautc'm'ati'c and semi automatic methods and machines. Another object of the invention'is to comprise animproved snap hook of the character described which is to be adapted to'be'manu factured' with improved facility by mass" production methods and at lesser cost corripa red to snap hooks of the prior art. v

Another object of the invention is to provide improved methods for fabricating snap hook de vices of the character referredtoherein'above. Other objects and advantages of the invention will appear" in the specification hereinafter.

In the drawings: 7

Fig. l is a fragmentary diagrammatic view of an initial stock piece forming operation of the method of the invention; 7

Fig. 2' is a diagrammatic illustration similar to Fig. 1 of a succeeding operation of the method of the invention;

Fig. 3 is a fragmentary diagrammatic illustra tio'n'of a step of the method of the invention followlngthe operation illustrated by Fig'. 2;;

Fig. 4' isa perspective of a partially formed hook-element resulting from the operations of Figs. 1-3 inclusive;

Fig. 5 illustrates in plan view preparation for the manufacturingoperation for furtherprocessing the partiallyformed hook of Fig. 4;

Fig. 6 is a side elevation corresponding to Fig. 5';

Fig. 7 is a view taken'along line VII VII or Fig. 6, illustrating application of alwelding process to the partially completed 11601; device;

Fig. 8' is a plan vle'w of a welded hook device upon c'ompletionof the operation illustrated by Figs. 5-7' inclusive; Y

Fig. 9 is'a' fragmentary diagrammatic view showing in side elevation the partially completed hook device of Fig. 8 in processofbeing further shaped towards itscoinpleted form; I

Fig. 10 is a section taken along line X-X of Fi s;

rig. =11 is afragi entaiy diagrammatic view i perspective showing the hook" device following the" process illustrated by Figs. 9-10 and in preparation for performance thereon'of a final assembly and fabricating operation;

Fig. 12 is a side elevation corresponding to Fig. 11)

Fig. 13 is a. section taken along line XIII-XIII of Fig. 12; and' v Fig. 14 is a perspective of a completed sn-ap hook of the invention.

As illustrated in the drawing, the invention relates to methods and means for producing in large quantities snap hook devices of the type comprising Wire or rod stock which has been initially cut to standard lengths and thenbe nt so as to form a hook device comprising side-biyfside leg portions terminating in an eye-shaped end for connection to a harness strap or the like. Aleaf spring guard is separately fabricated and mounted upon the hook body in conjunction with the operation of finally shaping the latter, so as to comprise an'integr'ally assembled unit ofim' proved form. n b p For example, Fig. 1 of the drawing illustrates at IS a length of wire stock such as'may have been previously'cut to suitable length'fro'r'n either coiled wire 'or rod sto 2k and then brought to rest in centered operative position as shown in Fig. 1 upon a forming die IS. The die I6 is provided with a pair of parallel abutments iii-i8 which extend from the body of the die and are rounded at their inner corners whereby the die Hi may be powered to force the stock piece I5 to bend around a ram block 20, the stock piece [5 being thereby displaced into the space betwe'enthe die abutments l8-l8 so as to be initially bentinto a U' shape as indicated at22. While the die'and block devices are maintained'so as to hold'the bent stock piece in position interiorly of' the die 16, a pair of rams 24-24' arebrought to bear laterally against the upstanding leg portions of the stock'pieceto converge thereuponso as to deform the legsinwardly and against one an other so as to complete the formation of an eye-shaped portion 26 and to dispose the legs of the stock piece in sideby-si'de extending relation "as indicated at 28--28'(Fig.'2).

The partially formed hook is thereupon'supp'ortedupon a' pedestal 32 having a downwardly rounded nose 34 (Fig. 3). A cam block"'36"is stationarily mounted above the position 'of the extending legs of the partially formed hook ahead of the pedestal 32 and in the path ofrnotion of an inclined end' portion '38 of}; ram ll! which is pivotally mounted by meansoija bearing upon aftraveler 44 which is 'a-daptedfto ".tactbetween the leg ends.

current around through the entire hook body is be power driven to reciprocate in directions horizontally as viewed in Fig. 3. A tension spring #5 connects to the ram ahead of the pivot connection 42 so as to normally maintain the ram in the horizontal attitude thereof as shown in Fig. 3. However, upon motion of thetraveler to the left as viewed in Fig. 3, it will be understood that the sloping end 38 of the ram 40 will be deflected obliquely downwardly by the cam 36. whereby the leading end portion of the ram 40 will; bear initially downwardly and then rearwardly against the ends of the hook legs 28' so as to curl the latter downwardly and thence rearwardly into the deformed shapesthereof indicated at 46 in Fig. 3. The leading end of the ram 40 is grooved as indicated at .48 so as to receive the hook legs 28-28 in guided "relation therein during the hook end forming operation. Thus. the hook stock piece is formed into the shape illustrated by Fig. 4; and particular attention is called to the fact that due to the natural resiliency of the metal of the stock piece there is an inevitable tendency for the legs 2828 to spread slightly when released from the die and ram devices, thus providing a gap between the hook end portions of the legs as indicated a 50 in Fig. 4.

Figs. 5-6-7 diagrammatically illustrate performance of the next step of the method of the invention wherein the ends of the legs of the hook device are pressed together and then welded as indicated at 52 in Fig. 8 to comprise an integral structure. This is accomplished by placing the leg;

a bolster 62 carried integral with the base 60. An

inner die 64 is set interiorly of the hook andan portion of'the hook therebetween into the sectional shape thereof shown at 68 in Fig. 10. Thus, the hook end is formed with a smoothly rounded outer surface as indicated at it in Fig. 11 and ends between a pair of converging electrodes -55 which are grooved as indicated at 56 so as to accurately engage upon the hook legs in firmly anchored relation prior to exerting thereagainst leg-converging pressures.

placed toward one another so as to spring the hook legs toward contacting relation the electrode cur- As the electrodes 55-55 are progressively disandthe resistance of the hook stock to such current flow results in a'preliminary heating of the stock. At the time of direct contact between the hook ends. however, the electrode current passes almost entirely directly through the con The former flow oi thereby short circuited and the pressure exerted by the converging electrodes combines with the heat thereby developed to cause the hook ends to be welded together. The current is then cut oil to permit the welded connection to cool slightly,

whereupon the electrodes are retracted, leaving the welded hook in the form illustrated by Fig. 8. As the residual heat dissipates from the body of method of the operation comprises forging of the i the formed hook it provides a stress relief effect I welded portion of the hook end into such shape as to provide an improved cap shape for the spring guard to be subsequently assembled upon the hook body. As shown in the drawing, this step of the method of the operation may be performed by resting the hook upon a base 60 while setting the I curved hook end portion 46-46 thereof against a grooved inner surface as indicated at E2 in Fig. 11, whereby to be adapted to receive therein the free end of a guard device such as is designated generally at 15 in Fig. 11.

The spring guard device T5 will have been previ. ously fabricated to the form thereof shown in Fig. 11 whereby to comprise a leaf spring body having at one end a reversely bent back portion 76. A collar device 18 is provided to encircle the back 16 of the guard and the leg portions :2228 of the hook body so as to hold the spring guard in operative position thereon shown in the assembled view at Fig. 14. Referring again to 11, particular attention is called to the fact that the .hook forming operations prior to this final assembly'step of the method of the invention is particularly designed to avoid closing of thehook end portion to the final position thereof so as to enable the operator to slip-fit the guard piece over and around the hook body and to thereby firmly clamp the guard thereon, as shown at 82 in Fig. 14. Fig. 13 illustrates, in side elevation, operation of the ram devices til-89 for clamping the ears 18-18 of the guard spring 15 upon the body of the hook.

A press 84 is thereupon brought to bear downwardly (Fig. 11) against the guard and hook end portions so as to interfit these parts and simulta neously bend the hook end into its final hook shape whereby to prevent subsequent disengagement of the guard from-the hook end. For this purpose, as shown in Figs. 1112 .,the press 8 is provided with a leading abutment 85 which engages only the guard spring so as to initially press the latter down sothat when the body of the press 84 engages the end id of the hook to depress the latter into finally closed position, the hook end will slip over the guard spring 75 as shownv in Fig. 14. A bolster 86 is preferably provided for this latter operation to engage within the eye portion 26 of the hook device so as-to posttively position the latter relative to a base plate 88 which opposes the press block 8 3.

Thus, it will be appreciated that the method of the invention is particularly adapted to full use of automatic type machines and shop practices for rapid production of snap hook and like devices in large quantities; and that the hooks produced thereby are of improved strength characteristics compared to prior art hooks made from similar stock and to similar dimensions. It will be understood that whereas the invention has been illustrated and described hereinabove in exemplification only, various changes may be made therein Without departing from the spirit of the invention and the scope of the appended claims.

I claim: v 1

l. The method of forming a book from wirelike stock comprising cutting a length of stock, then cold bending the latter into U-shape by ramming i-t intermediately of its ends between a concave die and a press block, then cold pressing the extending leg portions of the stock inwardly and around the press block to form the legs to extend outwardly in substantially side-byside relation having their inner ends substantially in contact and their outer ends slightly spread apart then cold-bending the outer spread ends of the legs reversely to provide a pair of hooked leg formations, then forcing the spread ends of the legs into firm mutual contact by means of a pair of opposed electrodes and then applying an electric current to said electrodes thereby welding the hooked leg ends together while providing beneficial heat treatment of the cold-bent portions of the stock.

2. The method of forming a hook from wirelike stock comprising cutting a length of stock, then cold bending the latter into U-shape by ramming it intermediately of its ends between a concave die and a press block, then clod pressing the extending leg portions of the stock inwardly and around the press block into self-abutting relation to form the legs to extend in substantially side-by-side but slightly diverging relation, then cold-bending the leg ends reversely to provide a pair of hooked leg formations, then pressing a pair of opposed electrodes against said hooked leg ends so as to squeeze them together while directing an electric current to fiow between said electrodes thereby welding the hooked leg ends together while providing beneficial heat treatment of the cold-bent portions of the stock, then forging the welded end portion of the formed hook to provide a groove along the inner surface thereof, and then mounting upon said formed hook a hook guard device comprising a leaf spring cantilever mounted at one end upon said hook with the opposite end of said guard spring disposed to rest within said grooved hook portion.

3. The method of forming a hook comprising cut-ting a length of stock, then cold bending the latter generally into U-shape and then finally into return bend hook form with the extending leg portions of the stock arranged in substantially side-by-side relation but diverging from their inner ends outwardly then forcing the diverging legs into firm mutual contact by means of a pair of opposed electrodes, and then directing an electric current flow between said electrodes thereby welding the leg ends together while providing beneficial heat treatment of the cold-bent portions of the stock.

4. The method of forming a hook from wirelike stock comprising cutting a length of stock and then bending the latter into U-shape by ramming it intermediately of its ends between a concave die and a press block, then cold pressing the extending leg portions of the stock inwardly and around the press block into selfabutting relation to form the legs to extend in substantially parallel side-by-side but slightly diverging relation, then cold-bending the leg ends reversely to provide a pair of hooked leg formations, then pressing a pair of opposed electrodes against said leg hook ends at the outer sides thereof so as to displace the latter together while directing an electric current to flow between said electrodes thereby initially heating the hook body and then welding the hooked leg ends together while providing beneficial heat treatment of the cold-bent portions of the stock, and then forging the Welded end portion of the formed hook to provide an integral welded smooth end structure grooved along the inner surface thereof.

5. The method of forming a hook from wirelike stock comprising cutting a length of stock, then bending the latter into U-shape by ramming it intermediately of its ends between a concave die and a press block, then pressing the extending leg portions of the stock inwardly and around the press block into self-abutting relation to form the legs to extend in substantially side-byside relation, then bending the leg ends reversely to provide a pair of open hooked leg formations, then welding the hooked leg ends together and then forging the welded end portion of the formed hook to provide a groove along the inner surface thereof, then mounting upon said formed hook a hook guard device comprising a leaf spring cantilever mounted at one end upon said hook with the opposite end of said guard spring disposed to extend eXteriorly of the curve of said forged welded hook end portion, then depressing the free end of said leaf spring to within the curve of said hook end portion, and then bending said hook end portion to a further closed position with the free end of said leaf spring disposed within the grooved hook end.

ARCHIBALD L. MoKINNON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS 

